Support Swift version 6.4 (#6637)

Author: SimplyDanny

Source/SwiftLintCore/Models/SwiftVersion.swift

@@ -89,6 +89,8 @@ public extension SwiftVersion {
     static let sixDotThreeDotOne = SwiftVersion(rawValue: "6.3.1")
     /// Swift 6.3.2
     static let sixDotThreeDotTwo = SwiftVersion(rawValue: "6.3.2")
+    /// Swift 6.4
+    static let sixDotFour = SwiftVersion(rawValue: "6.4.0")
 
     /// The current detected Swift compiler version, based on the currently accessible SourceKit version.
     ///

Tests/FrameworkTests/SwiftVersionTests.swift

@@ -5,7 +5,9 @@ import XCTest
 final class SwiftVersionTests: SwiftLintTestCase {
     // swiftlint:disable:next function_body_length
     func testDetectSwiftVersion() {
-#if compiler(>=6.3.2)
+#if compiler(>=6.4)
+        let version = "6.4.0"
+#elseif compiler(>=6.3.2)
         let version = "6.3.2"
 #elseif compiler(>=6.3.1)
         let version = "6.3.1"